JPH01204251A - Method of looking up recording medium - Google Patents

Abstract

PURPOSE: To prevent loss of time and to shorten search time by reducing the traveling speed of a recording medium each time its traveling direction is switched in both forward and backward directions and generating a report signal indicating retrieval of a target position when it is passed last. CONSTITUTION: In a retrieval method to be applied to a data recorder, which records and reproduces for example a data from a computer 3 using a rotary head type digital audio tape recorder(DAT) 1 in accordance with DAT format, the traveling speed is reduced of a recording medium 15 such as a magnetic tape, with its position detected while the medium 15 is run alternately in both forward and backward directions, with a report signal generated indicating a search completion immediately after a target position is passed last, and the target position is thereby detected. Consequently, there is no waiting time in which the recording medium is at a standstill, with the report signal generated immediately when the target position is sensed. Thus, with the recording medium 15 traveling, the next command signal can be received, reducing the retrieval time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is a recording device suitable for use when a rotary head type digital audio tape recorder (DAT) is used as a data recorder for recording and reproducing data sent from a computer, for example. The present invention relates to a medium search method.

[Conventional technology]

In a computer, in order to protect (back up) data written on a hard disk, this data is transferred to a data streamer (data recorder) and recorded once a day.

Conventionally, ordinary analog audio tape recorders have often been used as data recorders. but,
This analog audio tape recorder consumes a large amount of magnetic tape and has a low data rate (speed) during recording, so transfer and recording operations take time. This analog audio tape recorder also features fast search (
Since search operations cannot be performed, it takes time to search for the start portion of desired data.

Therefore, a helical scan type digital audio tape recorder using a rotating head, so-called DAT, is used as a data recorder. D.A.
When the T is used as a data recorder, data from the host computer is converted to DAT format data before being recorded. In the DAT format, one frame consists of two inclined tracks formed during one rotation of two heads with different azimuth angles, and this frame is used as a unit for 16-bit P.
CM audio data is layered alternately in increments)
It is recorded. Furthermore, auxiliary sub-data is also recorded. In this case, as described later, each track has P
A main area for recording CM data and a sub area for recording sub data are provided. This D
AT has a high-speed search function as described below.

A high-speed search operation using a conventional DAT was performed by the method shown in FIG.

As shown in FIG. 11, position signals "1" and "2".

When performing a search with the target position of a magnetic tape (15) on which "3", etc. are recorded as "5", for example, the position signal is detected while the tape (15) is running at 20,000 times the speed, and the position When "4" is detected and a stop signal is sent, the tape (15) passes through the target position "5" and then stops. Therefore, the tape (15) is reversed and run in the opposite direction at 16 times the speed, and when the target position "5" is detected and a stop signal is sent, the tape (15) passes the target position again and stops. . Then, when the tape (15) is reversed and run at triple speed, the target position is detected and a stop signal is sent, the tape (15) slightly passes the target position and stops.

At this time, a search end signal is output and the next command signal is made to wait.

When a command signal is input during this waiting state, the magnetic tape (15) runs at a constant speed, accurately detects the beginning of target position "5", and stops.

[Problem to be solved by the invention]

Conventional high-speed search operations are performed as described above, and since the magnetic tape remains stopped after the search end signal is output until the next command signal is input, there is a loss of time and the efficiency of the search operation is reduced. was making things worse.

The main objective (problem) of the present invention is to avoid wasting time (
An object of the present invention is to provide a recording medium search method that allows search operations.

[Means to solve the problem]

The present invention is a retrieval method applied to a data recorder that records and reproduces data from a computer using DAT according to the DAT format, for example, by reducing the running speed of a recording medium such as a magnetic tape and alternately moving the recording medium in both forward and reverse directions. The position is detected while the vehicle is running, and immediately after passing the target position, a report signal indicating the completion of the search is generated to detect the target position.

[Effect]

There is no waiting time when the recording medium is in a stopped state as in the past, and a report signal is generated immediately when it is deemed that the target position has been reached, so the next command signal can be received while the recording medium is running. Search time is reduced.

〔Example〕

FIG. 1 is a block diagram showing the configuration of an apparatus when a DAT is used as a data recorder.

In the figure, (1) is a DAT, (2) is an interface bus, (3) is a host computer, (4) and (
5) indicates an internal bus. DAT (1) mainly consists of a recording/reproducing section (6), a recording amplifier (7), and a reproducing amplifier (
8), signal processing circuit (9), RAM (10), data control unit (11), interface board (12),
System control section (13), servo motor drive circuit (1
4) etc.

The system control unit (13), signal processing circuit (9), and data control unit (11) use an absolute frame number (AFNO).

Mode indication, logical (relative) frame number (LFNO)
, data transfer instructions, and other predetermined signals are exchanged with each other.

Although not shown, the recording/reproducing section (6) has a rotating head drum, and a magnetic tape is wound around the drum in an angular range of about 90'' and is transported by a capstan. Two heads A and B with different
is provided, and two inclined tracks are recorded on (or played back from) the tape during one rotation of the drum.

Digital data supplied from the host computer (3) via buses (5), (2) and (4) is input to the interface board (12) and then sent to the data control unit (11) and RAM (10). ), signal processing circuit (9)
etc., undergo predetermined signal processing according to instructions from the system control unit (13). Thus, the above-mentioned DAT
Conversion to format is performed. This converted signal is supplied to a recording/reproducing section (6) via a recording amplifier (7), and is recorded on a magnetic tape by heads A and B.

Signals recorded on the magnetic tape are reproduced by heads A and B, and the reproduced signals are supplied to a signal processing circuit (9) via a reproduction amplifier (8). The digital data obtained by inversely converting the reproduced signal by the signal processing circuit (9) is sent to the data control section (11) and the interface board (12).
and is supplied to the host computer (3) via buses (4), (2), and (5).

FIG. 2 shows the DAT format on magnetic tape in the device described above.

During one rotation of heads A and B, two inclined tracks TA and TIl are formed from the bottom of the magnetic tape (15) as shown by arrow a in FIG. These two tracks T
A and T8 constitute one frame. One track TA (or 'r) consists of 196 blocks,
One block also consists of 288 bits. Of these, 34 blocks at both ends are sub-areas (second), and 128 blocks at the center are main areas.

Each sub-area is further divided into several sections.

More specifically, starting from the bottom of the track, there is a margin section, a subcode PLL preamble section, a first subcode section, a postamble section, a gap section between adjacent blocks, a tracking (ATF) signal section, a gap section between adjacent blocks, and a data section. A PLL preamble section, an inter-adjacent block gap section, an ATF signal section, an inter-adjacent block gap section, a subcode PLL preamble section, a second subcode section, a postamble section, and a margin section are provided. Of these, the first and second subcode sections are composed of eight blocks, and the other blocks are each composed of a predetermined number of blocks. Please note that the length of each section is not shown accurately in Figure 2.

The main area consists of 128 data blocks. FIG. 3 shows the data format of the main area. As shown in the figure, one data block consists of an 8-bit synchronization signal, an 8-bit PCM-ID (ID is an abbreviation for identification signal) (W,),
It includes an 8-bit block address (W2) and an 8-bit parity section, and following this, main data is recorded in a <256-bit section. When processing audio signals, this main data is 16-bit PCM data for the L and R channels. This 16-bit main data is interleaved (alternately recorded) with parity in the main areas of tracks TA and TB (one frame).

In this case, approximately 5760 bytes of data are recorded in the main area of one frame. When using the DAT as a data recorder, data from the host computer (3) is converted to 16-bit data and processed in the same way as PCM data, so these data must be formatted as shown in Figure 4. recorded in the main area of one frame. FIG. 4 shows the data format of the main area for one frame.

More specifically, as shown in FIG.
The bytes are divided into words (0-1439) each consisting of 4 bytes (32 bits). These words are 16 bits (2 bytes) and R
divided into channels. The first word (4 bytes) of this format is used as part of the header, and the 4 bits near the MSB of the first half byte of the L channel of this header are used as the format I which indicates the format of the data recorder.
Let it be D. The remaining 4 bits of this byte are undefined.

The remaining 1 byte of this L channel is used as a logical frame number (LFNO) section. The LFNO in the 8-bit section of each frame represents a binary value indicating one of the frame serial numbers 1 to 23 in a unit (one group) of 23 frames. Part of the above header R
The same data as the L channel is also allocated to the channel.

A total of 5756 bytes of data is provided in the next 1 to 1439 words, and the data signal from the host computer (3) is sent every 4 bytes to I)olDllDffilD31...
+D5755 is recorded in each word sequentially.

Next, the logical frame number (LFNO) will be described.

Since each LFNO section indicates one of the frame serial numbers 1 to 23 in units of 23 frames, the frame numbers 1 to 23 repeatedly appear every 23 frames.

When using units numbered by such LFNO, it is possible to divide each predetermined amount of data.
) can be easily detected, facilitating signal processing and high-speed searching.

Next, the data formats of the first and second subcode sections in the subarea will be described.

The first and second subcode sections each consist of eight subcode blocks and can record 2048 bits of data.

FIG. 5 shows the format of each subcode block. Each 8-bit synchronization signal, Wl.

After recording W2 and parity, 25 including parity
Record 6-bit subcode data.

The subcode data consists of four packs of 8x8 bits (8 symbols) each.

The subcode blocks have even and odd block addresses, and the contents of W and W2 are different in each block. The pack numbers (1 to 7) are as shown in Figure 5.
It is attached through even and odd blocks. The eighth pack contains a C code for error detection.

Wl of an even block consists of a 4-bit area ID and a 4-bit data ID, and W2 of the same block consists of a high-order 1 bit rlJ, a 3-bit pack ID, and a 4-bit block address. The Wl of an odd block consists of a 4-bit undefined part and a 4-bit format ID, and the W2 of the same block consists of a high-order 1 bit rlJ, a 3-bit all "0" code, and a 4-bit block address.

Each pack 1-7 is divided into 8 words of 8 bits. Each word includes a code indicating the read (lead-in) area at the start of recording on the tape, a code indicating the read-out (read-out) area at the end of recording, a code indicating the recording date, an absolute frame number, along with parity. Contains various codes such as logical frame number.

FIG. 6 shows the format of pack 1 in seven packs of subcode blocks, and FIG. 7 similarly shows the format of pack 2. As shown in FIG. 6, pack 1 consists of eight 8-bit words PC1-PCB. A pack number (here, "roool" indicating pack 1) is assigned to the upper four bits of the word PCI, and the next two bits are undefined. The following lower 2 picks - (P, M)
is multiple recording of data across multiple units (multiple recording).
ple-write access). The following words PC2 and PC3 (16 bits) are group counted. This GPC is a value obtained by counting the number of units (hereinafter referred to as "groups") in units of 23 frames from the front end of the tape.

A file mark count FMC is assigned to the following words PC4 to PC7 (32 bits).

A file mark indicates a division of a predetermined amount of data sent from a host computer. The file mark count FMC is a value obtained by counting the number of file marks from the front end of the tape until the count of the group count GPC is completed every 23 frames.

The last word PCB is assigned the parity for words PCI-PC7.

As shown in Figure 7, pack 2 consists of eight words PCI~
Consists of 8 PCs. The upper 4 bits of the word PCI contain the pack number ('0OIOJ, which indicates pack 2).
will be assigned. Words PC2 and PC3 (16 bits) are assigned a save set mark count SSMC. The data recorded by the data recorder during one backup operation is stored in one save set.
5et), and one save cent mark is sent from the host computer for each save set. The save set mark count SSMC indicates the value obtained by counting the number of save set marks from the leading edge of the tape until the count GPC is completed every 23 frames. A record mark count RMC is assigned to the following words PC4 to PC7 (32 bits). Record marks are marks sent from the host computer for each predetermined amount of data. record mark
Count RMC indicates a value obtained by counting the number of record marks from the front end of the tape until counting GPC is completed every 23 frames. The last word PC8 is assigned the parity for words PCI-PC7.

In this specific example, as described above, packs 1 and 2 have four count values GPC, F, respectively indicating data divisions.
MC, SSMC and RMC are provided. In other words,
These count values represent four types of units. These units are not particularly related to data length (recording length on tape), but have their own predetermined lengths.

Count FMC, SSMC and RMC are Callan) GP
It is expressed in relation to C.

FIG. 8 shows the relationship between count GPC and SSMC.

The number of save set marks from the leading edge of the tape is recorded as a count SSMC at the time when the group count is completed every 23 frames, facing all 23 frames including that time and making up the group. In the case of FIG. 8, the count of the save set mark continues to be 7 even after the counting of the GPC ■ group is completed. Therefore, SSMC■ is recorded facing all 23 frames of the GPC■ group. The SSMC ■ save set is
It spans two groups: GPC■ and GPC■. Therefore, the count SSMC is 46 of these groups.
Recorded facing the frame.

The relationships between the other counts FMC, RMC and count GPC are also determined in the same manner as in FIG. FIG. 9 shows the relationship between the group count and other unit counts and the search method. FIG. 9A shows the count G for each group.
Examples of instructions for P C, RM C, F MC and SSMC are shown.

Therefore, the above counts GPC, FMC.

Since SSMC and RMC are selectively detected, high-speed search operations are possible.

Next, the high speed search method according to the present invention will be explained in detail with reference to FIGS. 9 and 10.

High-speed search operations include an FF search operation in which the tape is searched by fast forwarding in the FWD (forward) direction, and an FF search operation in which the tape is searched in the forward direction.
This includes a REW search operation in which a search is performed by quickly rewinding in the W (reverse) direction. FIG. 9B shows an example in which the search is performed from the FF search operation, and FIG. 9C shows an example in which the search is performed from the REW search operation. In these examples, F as the target position
Given MC=4, to detect the target position, first G
A count GPC is used to detect the boundary position between PC8 and GPC9.

FIG. 10 is a flowchart showing the operation of the system control unit (FIG. 1) when performing FF and REW searches. In the figure, tp indicates the target position expressed in FMC, pp indicates the current position expressed in FMC, and GP
C, indicates the current GPC, and 'GPC, the immediately previous GPC. Therefore, when the tape is running, the current GPC becomes the GPC when the next GPC is detected.

In FIGS. 9 and 10, when the high-speed search routine starts in step (1), it is checked in step (2) whether tp>pp, that is, whether the current position is before or after the target position. If tP>PP and the current position is in front of the target position, step (3) OFF search operation and subsequent steps are executed. Further, if tp≦pp and the current position is after the target position, the REW search operation of step (24) and the steps following this are executed.

In the FF search operation, the tape is fast-forwarded at 200x speed to detect the count FMC. This fast forwarding operation is performed in step (4) until tp≦pp, and it is determined whether the tape has reached or passed the target position. If YES in step (4), a stop signal or a signal to rewind the tape at 166x speed is sent to the tape drive in step (5). In this way, the tape passes the target position and stops.
It is then rewound so that during FMC detection the tape is 16
Runs 6 times faster. GPC is detected in step (6),
Sequential GPC.

and GPc2 are determined. This 16 times stray running continues until tp>pp in step (7), that is, until it is determined that the target position has been passed again. If YES in step (7), then in step (8) GPc2−GPC,=
Check whether it is 1. Immediately after tp > PP in step (8) GP CI - GP Ct = 1, that is, GPC1
When it is confirmed that GPC2=9 and GPC2=8, it is considered that the tape has reached the target position.

In step (9), connect the bus (bus) to the host computer.
to report that the target position has been detected (good report). When the waiting time of 60 milliseconds has passed in step (10), the next command signal is waited for in step (11). When the next command signal is received in step (11), step (12)
), the operation is executed according to the command signal. In this operation, the target position "4" is searched by detecting the count FMC while advancing the tape at a constant speed. Step (11
), if no command signal is input, the tape stops at step (13) and the routine ends at step (14).

GPC in step (8) due to data loss etc.
If B-GPC,≠1 is confirmed, the flow advances to step (15), feeds the tape in the forward direction, and continues to step (16).
) to detect GPC. In step (17), tp≦pp
Step (16) is repeated until , ie, the tape passes the target position again.

If tp≦pp is confirmed, GPc is determined in step (18).
, -GPC, = 1 is checked. Step (18)
If the answer is YES, it is assumed that the target position has been detected, and this is notified to the host computer as a good report in step (19). In step (20), the tape is reversed and waited for 600 milliseconds, and then the flow proceeds to step (11). GPC in step (18).

- If GPC,≠1 is confirmed, a defect report is made in step (21), the tape is stopped in step (21),
The routine ends at step (23).

If no in step (2), a REV search operation is performed. In step (24), the tape is
Detect the count FMC while rewinding at 00x speed. This rewinding operation is continued until it is determined in step (25) that tp>PP and that the tape has passed the target position. If yes in step (25), step (26)
) sends a stop signal or a signal for running the tape in the forward direction at 166x speed to the tape drive device. Therefore, the tape stops after passing the target position, reverses itself, and runs at 166 times the speed while detecting the FMC. This 16-fold stray running continues until it is determined in step (27) that tp≦pp and the tape has passed the target position. If YES in step (27), the tape running direction is reversed in step (28) and the tape is run at triple speed. In step (29), GPC is detected and GPC and GPC2 are detected one after another.
is determined. To run at 3x speed, set tP in step (30).
>PP and continues until it is determined that the tape has passed the target position. If YES in step (30), then in step (31) G P Cz G P Cr = 1
Find out if. Immediately after tp>pp is confirmed in step (30), GPC, -GPC2-
1, that is, GPCZ=9. When GPC,=8, it is assumed that the target position has been reached. In step (32), the detection of the target position is reported to the host computer via the bus. After the waiting time of 200 milliseconds has passed in step (33), the next command signal is waited for in step (34). When the next command signal is received, the operation corresponding to the command signal is executed in step (35). In this operation, the target position "4" is searched by detecting the count FMC while feeding the tape at a constant speed. Step (34)
If no command signal is received at step (36), the tape is stopped at step (36) and the routine ends at step (37).

GPC is performed in step (31) due to data loss.

- Once GPC2≠1 is confirmed, the flow changes to step (15
) The following routine is entered and the operations described above are executed.

In the above specific example, the count GPC and FMC were used as position signals of the recording medium, but the above SSMC and RMC
Of course, it is also possible to use the search operation.

〔Effect of the invention〕

As mentioned above, step (8) in the FF search operation
Or, immediately after determining that the target position has been reached in step (31) in the REW search operation, steps (9) and (
Since a report signal indicating a good result is generated at step 32), the next command can be quickly received while the tape is running. Therefore, there is no time loss and the search time is shortened.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a configuration example of an apparatus using the present invention, and FIG. 2 is a DA on a magnetic tape in the apparatus of FIG.
Figure 3 is a diagram showing the data format of the main area in Figure 2, Figure 4 is a diagram showing the data format of the main area for one frame, and Figure 5 is a diagram showing the data format of the main area in Figure 2.
A diagram showing the format of each subcode block in the diagram,
Figure 6 is a diagram showing the format of pack 1 of the subcode block, Figure 7 is a diagram showing the format of pack 2, Figure 8 is a diagram showing the relationship between count GPC and SSMC, and Figure 9 is a diagram showing the format of pack 2. Figure 10 is a diagram showing the relationship between group counts and other unit counts and the search method.
Flowchart showing the operation of the system control unit shown in FIG.
FIG. 1 is a diagram showing a conventional search method. (15) Recording medium, GPC, FMC, S, SM
C. RMC...Position signal (unit count signal), tp
...Target count value, pp...Reproduction count value.

Claims (1)

[Claims] 1. A recording medium on which a position signal is recorded is alternately run in both forward and reverse directions, and each time the running direction is changed, the running speed is reduced, and the position signal is detected to detect the target on the recording medium. A recording medium search method for detecting a position, characterized in that after detecting that the target position has been last passed, a report signal indicating that the target position has been searched is generated. Method. 2. The recording medium according to claim 1, wherein main data is recorded in a first area of each unit in the recording medium, and a unit count signal and various count signals are recorded in a second area of each unit. Method. 3. The method of claim 2, using DAT, wherein said first area is a PCM area and said second area is a subcode area. 4. Compare the count value reproduced from the recording medium with the target count value, control the direction and speed of the recording medium based on the comparison output, and make the count value reproduced from the recording medium approach the target count. 2. The method of claim 1, wherein said report signal is generated after detecting a break in said unit count signal.